This invention relates to an optical assembly for use in a barcode reader and, in particular, to an adjustable apparatus for positioning a sharp line of illuminator in barcode space.
Although the advantages associated with light emitting diodes (LEDs) when used in barcode scanning equipment are well known, the level of the intensity produced by this type of lamp is relatively low when compared to other light sources, such as halogen lamps or arc lamps. In an effort to improve the effectiveness of light emitting diodes in this application, it is sometimes customary to employ a relatively large number of lamps aligned in one or more rows above or below the imaging lens. As a result, the target region, as well as the periphery of the target region, are flooded with excessive light energy. This approach, however, is space consuming and poses certain assembly and alignment problems.
Optical units have also been devised for providing coplanar illumination wherein the light emitting diodes are mounted in the same plane as the imager on both sides of the imaging lens. Light from the light-emitting diodes is further passed through magnifying lens to project the light onto the barcode target. Additionally, diffusers are used in association with the LEDs to more uniformly distribute the light within the target area. Here again, these optical units overcome many of the problems associated with LED illumination systems.
They nevertheless pose certain other problems relating to bringing the components together in assembly to provide compact, easy to install and adjust units suitable for use in a hand-held long range scanner.
It is, therefore, a primary object of the present invention to improve barcode readers.
A further object of the invention is to improve hand-held barcode scanners for long range illumination and reading of a barcode target.
A still further object of the present invention is to improve optical devices for use in barcode scanners which are capable of producing a sharply defined line of illumination in barcode space using light emitting diodes.
Another object of the present invention is to provide apparatus for positioning illumination within a desired location in barcode space.
These, and other objects of the present invention, are attained by an apparatus for adjusting the position of a line of light in barcode space that includes a support frame having a rear housing containing a solid state imager and a pair of support arms extending forwardly from the front of the housing. An imaging lens is mounted between the arms for focusing an image of a target in barcode space upon the solid state imager along the optical axis of the imaging lens. Illuminating LEDs are mounted on either side of the imaging lens for illuminating the target. The illumination is passed through a pair of cylindrical lenses that are adjustably mounted upon the distal ends of the arms so that the light can be selectively positioned in barcode space.